Electric switch gear



Feb. 8, 1938. w. V.'JEFFS 7 ELECTRIC SWITcH GEAR Filed Jan: '18, 1937 2 Sheets-Sheet 1 [Tn/enter":

WHliam V- J FPS,

by His Atborvwey.

Feb. 8, 1938. w. v. JEFFS 2,107,947

' ELECTRIC SWITCH GEAR Fired Jafi. 18, 1957 V 2 Shets-Sheet 2 William v J 95,

H'is Attcnrney.

Patented Feb. 8, 1938 UNITED STATES PATENT OFFIQE ELECTRIC SWITCH GEAR William Victor Jefis, Eastcote, England, assignor to General Electric Company, a corporation of New York Claims.

My invention relates to electric switchgear, more particularly to selecting and isolating switches for electric power circuits, and has for its principal object the provision of an improved,

5 simplified, compact and electrically eflicient switchgear of the character above referred to.

When it is desired to connect a feeder to a ring main there is usually provided at the point of connection. a selecting and isolating switch or both by means of which the feeder can be connected selectively to either side of the ring main at the point of connection or can be disconnected therefrom while completing or not the circuit of the ring main. It will be seen that three points of connection are provided and the usual arrangement heretofore provided for such connections has involved the use of a selecting and isolating switch or both, which may be oil-immersed,

if desired, and which comprised three: insulated 2Q conductors each connected to a switch blade, the switch blades co-operating with a centrally mounted insulating contact by means of which the connections above noted could be made. Where a polyphase circuit is under consideration,

the connections for each phase have been commonly arranged in such a manner that the central contact for each phase was mounted co-axially, being supported upon a single insulator designed to withstand the interphase potentials.

The present invention consists in providing a construction in which the central insulator is eliminated and according to the invention three pivotally mounted switch blades are supported upon the ends of the insulated conductors in such a manner that each switch blade is adapted to connect with a contact associated with the adjacent insulated conductor.

Preferably the arrangement is such that the insulated conductors each support a pivoted 4U switch blade and a contact adapted to be engaged by the switch blade pivotally mounted upon one of the adjacent insulated conductors, as by this means a symmetrical arrangement may be adopted. The switch blades are each provided with a suitable actuating device which may comprise a floating link pivotally connected at one end to the switch blade and at the other end to a crank arm carried by an operating shaft and the connections to the operating shaft may be 5 arranged so that each switch blade can be actuated by manually, or otherwise operated handles which are mounted close to one another, suitable interlocking means being preferably provided to ensure any given sequence of operations of the 55 switch blades.

My invention will be more fully set forth in the following description referring to the accompanying drawings, and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to 5 and forming a part of this specification.

Referring to the drawings Fig. 1 is a sectional end view 015 a three-phase selecting and isolating switch embodying my invention and Figs. 2, 3 and 4 illustrate diagrammatically applications of the lo invention.

The switch comprises a cylindrical casing l, preferably filled with insulating oil and having for each phase three insulated conductors 2, 3 and 4 respectively, each conductor being insul lated from the tank by a bushing 5. Each conductor at its inner and provides a pivotal support for a movable switching blade 6 and also a contact 1 adapted to be engaged by the link mounted on the next adjacent conductor viewed in a clockwise direction. It will be evident that the blades 6 could be mounted on collars secured near the ends of the bushings and connected electrically to the conductors, although the arrangement actually adopted is obviously simpler to construct. The switching links are each provided with a suitable actuating mechanism which may comprise a link 3, a bell crank or similar lever B pivotally mounted on a shaft i 0 suitably journalled in the casing and an actuating link indicated at l l. ,1 The insulated conductors are supported at an angle of 120 with respect to one another for the phase indicated and converge toward the center of the casing so that the switch blades are arranged about a substantially equilateral triangle. For the other phases, however, the upper bushu ings 5, 5a and 5b may have to be arranged in staggered relation in order to obtain the necessary spacing between the outer ends of the conductors 4. To obtain the necessary separation of the outer ends of the lower conductors the lower bushings 5 may be arranged at an angle to one another on the longitudinal axis of the tank I.

It will be seen that by operating the links 6 it is possible to interconnect any two of the contacts l at 2, 3 and 4 to interconnect all those contacts or to isolate all the contacts from one another. It will be understood, of course, that it will usually be necessary to provide suitable interlocking arrangements which would prevent the contacts from being interconnected in certain conditions.

The actuating mechanism for the links H are all arranged on the structure l2 arranged on the upper side of tank I, suitable operating shafts 13 which are journalled on the structure 12 extending outside this structure and being operated by external means (not shown).

Figs. 2, 3 and 4 of the drawings show three ways in which the improved isolator according to the invention may be employed. In Fig. 2 a transformer 39 may be connected to either of conductors 3! or 32 by closing the appropriate switches, or by closing all three switches a- T- connection may be efiected.

Fig. 3 shows an arrangement similar to Fig. 2 but in which a pair of the improved isolating switches are employed with a circuit breaker 33 interconnecting two of the contacts of the isolators. Transformers 35 and 3B are connected to two other terminals of the isolators whereby an arrangement is provided for a single breaker sub-station employing two transformers.

Fig. 4 shows a further arrangement in which two transformers 3'1, 38 can be connected to a ring main 39 to which are connected three ieeders M] by T-off connections, the ring main connection between the isolators having a circuit breaker ll so that any portion of the ring main can be cut out when desired and also that any of the individual circuit breakers can be iso-- lated without shutting down any other circuit or reducing the protection on the complete substation.

In case it is desired to effect earthing oi the circuits connected to the conductors 2, 3, ii, earth contacts may be arranged within the tank and supported directly on the tank wall the earth contacts being so disposed that on operating the switch blades 6 to an earth position, the outer ends of the blades make contact with the contacts supported on the tank. in the arrangement illustrated in Fig. 1, however, the earthing is eiiected by the external earthing blades l4, these blades for the lower conductors are mounted on shafts l and i5 which when rotated by the mechanism H and I8 respectively cause the blades on the respective shafts simultaneously to connect the contacts l9 on the outer ends of the conductors to the tank. Owing to the upper conductors not being in axial alignment a somewhat different arrangement is adopted. In this case the blades i l are each connected by links of which 29 and it only are shown to levers mounted on the operating shaft 22 by rotation of which these blades can be simultaneously operated.

While oil has been specified as the insulati fluid for filling tank other insulating liquids e. g. carbon tetrachloride may be substituted.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. Electric switchgear for isolating and controlling connections between a plurality of circuits comprising a casing, an insulating lead-i conductor bushing for each of said circuits extending within said casing so as to converge towards the center of said casing, and a movable switch element and a contact element mounted at the end of certain of said bushings arranged so that the switch element of one conductor is adapted selectively to engage the contact element of an adjacent conductor.

2. Electric switchgear for isolating and controlling the connections between a plurality of circuits comprising a casing containing an insulating liquid, an insulating lead-in conductor bushing for each of said circuits supported by and extending within said casing generally in a radial direction so as to converge towards the center of said casing, and a pivoted switch element and a contact element immersed in said liquid and mounted at the end of each of said bushings arranged so that the switch element of one conductor is adapted selectively to engage contact element of an adjacent conductor.

Electric switchgear for isolating and controlling the connections between three circuits comprising an insulator for each circuit conductor spaced approximately 1.20 degrees apart and extending generally in a radial direction so as to converge toward a common point, the converging ends of said insulators forming substantially an equilateral triangle, and a movable switch element and a contact element mounted at the end of each of said insulators arranged so that the sv itch element of one circuit is adapted selectively to engage the contact element of an adjacent circuit.

4-. Electric switchgear for isolating and control g the connections between three circuits corn sing a substantially cylindrical metallic casing containing an insulating liquid, an insulator for each circuit conductor supported by and extending within said casing generally in a radial direction so as to converge towards the center of said casing, the inner ends of said insulators defining a substantially equilateral triangle, a pivoted switch blade and a fixed contact mounted at the end of each of said insulators, and operating means disposed exteriorly of said casing for selectively actuating each switch blade with respect to the fixed contact of an adjacent insulator.

5. Electric switchgear for isolating and controlling the connections between a plurality of circuits comprising a metallic casing containing insulating liquid, an insulating lead-in conductor bushing for each circuit conductor supported by and extending within said casing so as to converge towards the center of said casing, a movable switch element and a contact element mounted at the end of each of said bushings arranged so that the switch element of one conductor is adapted selectively to engage the contact element of an adjacent conductor, and a grounding switch mounted on and exteriorly of said casing at certain of said bushings for selectively grounding the exterior ends of said bushings.

VJILLIAM VICTOR J EFFS. 

